Lens system for a gaussian photographic objective



uaus SYSTEM FOR A GAUSSIAN PHOTQGRAPHIC OBJECTIVE Filed Sept. 24, 1958 G. LANGE Nov. 14, 1961 2 Sheets-Sheet 1 j, 7?

29.10 PRIOR ART G. LANGE Nov. 14, 1961 LENS SYSTEM FOR A GAUSSIAN PHOTOGRAPHIC OBJECTIVE Filed Sept. 24, 1958 2 Sheets-Sheet 2 United States Patent 3,008,373 LENS SYSTEM FOR A GAUSSIAN PHOTO- GRAPHIC OBJECTIVE Giinther Lange, Konigsbronn, Wurttemberg, Germany,

assignor to Carl Zeiss, Heidenheim (Brenz), Wurttemberg, Germany Filed Sept. 24, 1958, Ser. No. 763,148 Claims priority, application Germany Sept. 25, 1957 1 Claim. (Cl. 88-57) It is known that the components lying in front of the diaphragm of a Gaussian photographic objective (basic objective) may be replaced by a lens system consisting of other components, for the purpose of obtaining an altered photographic objective with greater equivalent 1focalhlength but with approximately equal back focal engt The ditficulties arising in the development of systems of this kind grow in proportion to the ratio of the two focal lengths. If for instance the greater focal length is to be about 1.6 times the amount of the focal length of the basic objective, then multi-component systems must be provided if it is desired to obtain good image quality.

The investigations on which the present invention is based have shown that a good compromise between the individual aberrations can be attained if said lens system consists of at least three lens components separated by air spaces, of which at least one air space has the two lens surfaces of the components bounding it concave towards the diaphragm, the radii of each of said bounding surfaces lying between 0.1-f and 0.35 -f and the axial separations of its bounding surfaces lying between 0.01- f and 010-), wherein the algebraic sum of the refractive powers (An/r) of the two surfaces bounding the aforesaid air space has negative value and wherein the algebraic sum of the refractive powers of all the surfaces lying in front of this air space has negative value, and the partial system comprising all components lying in front of the said air space has negative focal length while the algebraic sum of the refractive powers of the surfaces lying between the said air space and the diaphragm has positive value wherein furthermore the axial separation between the surface bounding the said air space on the object side and the diaphragm is less than 0.35 X but greater than 0.02 X f where f signifies the equivalent focal length of the complete objective composed of the said lens system and the components behind the diaphragm of said basic objective including the diaphragm.

Good chromatic correction can be attained by designing the first lens in the shape of a dispersive meniscus lens which turns its concave side towards the diaphragm and shows a v-value less than 35. It is advisable to cement this first lens to the second, but approximately equal correction can be attained with a narrow air space.

In the following two embodiments are given of objectives which consist of a lens system according to the invention and of the remainder of the basic objective standing behind the diaphragm. The objectives are represented in FIG. 1 and FIG. 2. The basic objective corresponding to each is of prior art and is represented in FIG. 1a and FIG. 2a. In the Table I shown in the following the numerical values are given for the objective according to FIG. 1, in the Table II the numerical values for the objective according to FIG. 2, and in the Table III the numerical values for the basic objective according to FIG. 1a and FIG. 2a.

Therein are designated By L to L the lenses By r t0 r 4, the radii,

By d to d the axial separations, By n the refractive indices,

By v, the Abbe numbers,

2 By An/r, the refractive powers of the individual lens surfaces, By s the back focal length, and By 0, the aperture of complete objective.

The numerical values are standardised in such a way that for the focal lengths of the objectives according to the invention the value f=l results; this focal length is 1.6 times as large as the focal length of the basic objective.

In the embodiment I it is the air space between lens IV and lens V which shows the characteristics of the invention. In the embodiment II it is the air space between the lens V and lens VI.

Table l (FIG. I)

[so=0.42086 f=1.00 O=l:4]

Lenses Radll Axial m w An/r Separations n =+0. 62553 +1. 2872 L1 d1 =0. 03586 1.80518 25. 46

ii; =0. 00000 1 =+0. 44919 +1. 3175 L d3 =0. 14342 1. 59181 58. 25

d4 =0.00120 rs =+0. 31346 +1. 4818 L111 (is =0. 23784 1. 46450 65. 79

do =0. 04260 n =+6. 62412 +0. 0994 Lrv d1 =0. 09322 1. 65844 50. 84

da =0. 01912 r; =+0. 19777 +2. 9462 Lv d: =0. 07769 1. 58267 46. 46

rio= 0. 23171 +2. 5147 dio=0. 00000 m== 0. 23171 3. 1073 Lvr dn=0. 00956 1. 72000 50. 31

d1z=0. 07350 m= 0. 18671 3. 9004 Lvn dn=0. 01793 1. 72825 28. 34

du=0. 00000 n5= 8. 46122 0. 0879 Lviu d|5=0. 06932 1. 74400 44. 9D

(115 0. 00120 m=+8. 34027 +0. 0892 Lzx d1 =0. 05139 1. 74400 44.

Table II FIG. 2) [so=0.42086 /=1.00 O=1:4]

Lenses Radll Axial m r An/r Separations ri =+0. 70567 +1. 0224 L1 d1 =0. 04384 1. 72151 29. 28

dz =0. 00000 n =+0. 57368 +0. 9914 Lu d; =0. 18525 1. 56873 63. 12

d; =0. 02390 n 2. 13737 0. 3147 Lin di =0. 03586 1. 67270 32.23

do =0. 00120 n =-0. 34049 +1. 4689 L v d1 =0. 14976 1. 50013 61. 59

d; =0. 18370 n =+3. 56775 +0. 2085 Lv da =0. 01195 1. 74400 44.90

Ii1o=0. 03753 r =+0. 24631 +2. 5389 Lvr dn=0. 02390 1. 62536 35. 57

dl2=0. 07171 m= 0. 18671 3. 9004 Lvn dia=0. 01793 1. 72825 28. 34

m= 8. 46122 +0. 0861 dn=0. 00000 m= 8. 46122 0879 Lvm dn=0. 06932 1. 74400 44. 90

dus=0. 00120 ri1=+8. 34027 +0. 0892 Lu: di1=0. 05139 1. 74400 44. 90

3 Table, III.Basic objective (FIGS. 1a and 2a) Lenses Radll Axial Separam w tions m= +0. 38342 L): dm=0. 03944 1. 74400 44. 90

dzo=0. 00120 m=+0. 22512 Lxr dn=0.06693 1. 62041 60. 29

m:- eo Lxn d2 =0. 01315 1. 57501 41. 31 m=+0. 15155 "LI2|=0. 15896 m= 0. 18671 Lvn d1;=0. 01793 1. 72825 28. 34

d14=0. 00000 r 8. 46122 Lvm d =0. 06932 1. 74400 44. 90

m= 0. 25078 I die=0. 00120 n1=+8. 34027 Lrx d11=0. 05139 1. 74400 44. 90

1 claim:

A lens system adapted to replace the components lying in front of the diaphragm of a Gaussian objective (basic objective), said lens system forming in conjunction with the components lying behind the diaphragm of said basic objective and including the diaphragm an altered photographic objective which with approximately equal back focal length has a greater equivalent focal length than said basic objective, said lens system consisting of at least three lens components separated by air spaces, at least one of said air spaces having the two lens surfaces bounding it concave towards the said diaphragm, the radii of each of its bounding surfaces lying between 0.1-f and 0.35 -f, the axial separation of its bounding surfaces lying between 0.01-f and 0.1-f, the algebraic sum of the refractive powers (An/r) of its bounding surfaces having a negative value, the algebraic sum of the refractive powers of all the surfaces lying in front of the said air space having negative value, the partial system comprising all components lying in front of the said air space having negative focal length, the algebraic sum of the refractive powers of the surfaces lying between the said air space and the diaphragm having positive value, and the axial separation between the surface bounding the said air space on the object side and the diaphragm lying between 0.02-f and 0.35 f, where f signifies the equivalent focal length of the complete altered objective composed of the said lens system and the components behind the diaphragm of said basic objective including the diaphragm, the front component of said lens system being a compound component, the front lens element of which is a dispersive meniscus lens concave towards the diaphragm made of a glass having an Abbe-v-number less than 35.

References Cited in the file of this patent UNITED STATES PATENTS 2,662,447 Tronnier Dec. 15, 1953 2,780,139 Lange Feb. 5, 957 2,796,002 Klemt June 18, 1957 2,816,482 Lange Dec. 17, 1957 2,824,493 Klemt 'Feb. 25, 1958 2,824,494 Klemt Feb. 25, 1958 2,831,396 Klemt Apr. 22, 1958 FOREIGN PATENTS 472,234 Germany Mar. 5, 1929 1,013,890 Germany Aug. 14, 1957 1,014,753' Germany Aug. 29, 1957 

